Calling Stat on a non existent file returns 500 rather than 404

[tomqwpl]

Nomad version

v1.1.4

Operating system and Environment details

Windows 10

Issue

I'm trying to test for the existence of a file in an allocation directory.
I call:

nomadClient.AllocFS().Stat(alloc, filename)

If the file doesn't exist, this returns an error "Unexpected response code: 500".
Internal server error 500 isn't really an expected response to this, a 404 would be more expected.

Note that in general I seem to have to match the text of the error to detect the 404 case elsewhere, rather than there being a specific error type I can test for for example. Matching on the string of the error text feels fragile, but at least matching for a specific string containing 404 would be preferable to a more generic 500.

Reproduction steps

Expected Result

An error I can use to easily detect "not found"

Actual Result

An ambiguous error that could mean many things

[tgross]

Hi @tomqwpl! Ok, so I followed that code path and it hits the HTTP API, where it calls the server RPC, which calls the client RPC, which calls into the alloc dir functions that calls os.Stat (which is the operating system interface).

What we should be doing is capturing the error from the allocdir package at client/fs_endpoint.go#L148-L151 and converting that to a 404 if it's a "path not found" error. There'll also be an interaction with the sandbox check we need to think about.

[tgross]

I've shipped a fix as #11482 and that'll ship in the next regular patch version of Nomad.

[tomqwpl]

Cool. Thx.

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